1. Field of the Invention
This invention relates to a MIDI (Musical Instrument Digital Interface) signal transmitter, a MIDI signal receiver, and a MIDI signal transmitter/ receiver, for transmitting and/or receiving a MIDI signal for use in transferring performance information between MIDI instrument devices including performance devices, such as keyboards and MIDI guitars, tone generators, and sequencers.
2. Prior Art
A MIDI signal is a signal conforming to MIDI standards, which provides performance information having compatibility in respect of velocity information, tone information, and control information. The MIDI signal is used e.g. by a MIDI instrument system having a keyboard (MIDI instrument device) as a performance device and a tone generator (MIDI instrument device) separate from the keyboard, for control of the tone generator. In such a conventional MIDI instrument system, the keyboard and the tone generator are connected via a MIDI cable. When a note-on operation is made on the keyboard, i.e. when a key is depressed, a MIDI signal comprised of key-on information, pitch information, and velocity information is delivered from the keyboard via the MIDI cable to the tone generator. The tone generator generates a musical tone based on the MIDI signal.
However, a MIDI instrument system of this kind suffers from the following problems: First, in installing a MIDI instrument system, it is required to connect a keyboard and a tone generator via a MIDI cable to each other. The connection of these devices by the MIDI cable is in itself troublesome. This inconvenience is markedly increased when a keyboard is connected to a plurality of tone generators. Further, if the keyboard is connected to the plurality of tone generators by chain connection via "THROU" terminals provided on each tone generator for control of tone generation, a waveform of the MIDI signal transmitted by chain connection can deteriorate due to a difference in time between a rise and a fall of an electric signal occurring when photoelectric conversion is carried out by a photocoupler used in a MIDI signal receiver circuit of each tone generator, causing an error in the tone generator. Further, when a performer plays with a MIDI guitar or a keyboard of a handy type, a MIDI cable may stand in the way, thereby preventing the performer or operator from freely moving around to give a performance as he desires. This inconvenience spoils the merit of a light weight MIDI instrument device for ease of performance realized through the utilization of the MIDI signal. Moreover, according to the MIDI standards, transfer of the MIDI signal via the MIDI cable is possible within a limit of 15 m, and hence it is impossible to give a performance with a performance device, such as a keyboard, and a tone generator positioned apart from each other by a distance larger than the limit.